Pyrolysis gasoline (pygas) is a liquid by-product of ethylene production, formed by the steam cracking of crude oil fractions such as naphtha. Pygas generally consists of heavy (C5 to C14) saturated and unsaturated hydrocarbons; its unsaturated hydrocarbons include olefins, dienes, and aromatics. Pygas can be used as a gasoline blending stream; pygas is generally high octane and within the general gasoline boiling range of from about 100° to about 435° F. Pygas can also be the source of aromatics for petrochemical processes. For instance, BTX extraction yields the compounds benzene, toluene, and xylene.
Pygas can be subject to destabilization by the polymerization of its reactive olefins and dienes. A common practice at steam crackers is to stabilize pygas with phenylenediamine or other similar anti-oxidant in storage. A drawback to phenylenediamine is that it requires air to be active for stabilization. In addition, phenylenediamine can be converted to ammonia in the pygas treater section. This can lead to ammonia excursions in the treated product.
In view of the above it would be desirable to utilize a compound for the storage of pygas that neither requires oxygen nor produces ammonia.